Crystal Structure and Luminescence of a New Zn(II) Complex [Zn(L)(IPP)(H2O)]·2H2O Based on Nicotinate Derivative and 1,10-Phenanthroline Derivative①

WANG Xiu-YanLIU RuiLI Fang-YuanMENG Xiang-YueSUN Qing-HongZHAO Zhong-Yua(Key Laoratory of Preparation and Applications of Environmental Friendly Materials, Jilin Normal University, Siping 136000, China)(Department of Chemistry, Jilin Normal University, Siping 136000, China)

Crystal Structure and Luminescence of a New Zn(II) Complex [Zn(L)(IPP)(H2O)]·2H2O Based on Nicotinate Derivative and 1,10-Phenanthroline Derivative①

WANG Xiu-Yana,b②LIU Ruia,bLI Fang-Yuana,bMENG Xiang-Yuea,bSUN Qing-Honga,bZHAO Zhong-Yua,ba(Key Laboratory of Preparation and Applications of Environmental Friendly Materials, Jilin Normal University, Siping 136000, China)b(Department of Chemistry, Jilin Normal University, Siping 136000, China)

A new Zn(II) complex, [Zn(L)(IPP)(H2O)]·2H2O (1, H2L = 3-carboxy-1-carboxymethyl-2-oxidopyridinium and IPP = 2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenol), was synthesized under hydrothermal conditions and its structure was determined by single-crystal X-ray diffraction.It crystallizes in triclinic, space group P1 with a = 8.5023(17), b = 9.945(2), c = 15.573(3) ?, α = 95.87(3), β = 102.56(3), γ = 100.73(3)o, V = 1248.7(4) ?3, Z = 2, C27H22N5O9Zn, Mr= 625.87, Dc= 1.665 g/cm3, F(000) = 642, μ(MoKa) = 1.053 mm-1, R = 0.0474 and wR = 0.1352.In 1, one L2-, one IPP and one water molecule coordinate to the same Zn(II) atom to give a discrete complex with two lattice water molecules.Adjacent [Zn(L)(IPP)(H2O)]·2H2O molecules interact through π-π stacking between two IPP ligands to form a supramolecular chain.The N–H··O and O–H··N hydrogen bonds further stabilize the supramolecular chain structure of 1.The solid state luminescent property of 1 was also studied.

crystal structure, hydrogen bonds, π-π stackings, luminescent property;

1 INTRODUCTION

Crystal engineering of supramolecular complexes has attracted increasing attention because of the easily predicted π-π and hydrogen-bonding interactions in supramolecular synthons as well as their potential applications as functional materials in proton conduction, sensing, and catalysis[1-3].It is well known that the components of organic ligands act as an important role in the construction of metal-involved supramolecular architectures[4,5].In this regard, the aromatic polycarboxylates, such as 1,4-benzenebicarboxylic acid, 1,3,5-benzenetricarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid, have been extensively utilized in constructing coordination complexes[6-8].Very recently, nicotinic acid and its derivatives have received great interest from chemists because of their structural diversity and biological applications[9].The flexible 3-carboxy-1-carboxymethyl-2-oxidopyridinium (H2L), as a good candidate for the construction of coordination complexes, has received much less attention[10].On one hand, the H2L lignad could bridge the central metals in various coordination modes through carboxylate and hydroxyl oxygen atoms.On the other hand, the carboxylate and hydroxyl groups ofH2L ligands could be involved in forming intermolecular hydrogen bonds and result in supramolecular architectures[11].Especially, the combination of nicotinate derivative with 1,0-phenanthroline derivative will form robust supramolecular architectures via hydrogen bonds as well as π-π stackings.

On the basis of the aforementioned points, in this work, a new Zn(II) compound based on flexible H2L and N-donor ligand 2-(1H-imidazo[4,5-f][1,10]-phenanthrolin-2-yl)phenol (IPP), namely [Zn(L)(IPP)-(H2O)]·2H2O (1), was prepared under hydrothermal conditions.In addition, solid state luminescent property of 1 was also investigated at room temperature.

2 EXPERIMENTAL

2.1 Generals

All materials were of analytical reagent grade and used as received without further purification.Elemental analysis was carried out with a Perkin-Elmer 240C analyzer.The emission spectra were performed on a Renishaw inVia Raman Microscope.IR spectrum was determined on a Perkin-Elmer Spectrum One FTIR spectrometer.

2.2 Synthesis and crystal growth

A mixture of ZnSO4·7H2O (0.25 mmol, 0.072 g), IPP (0.2 mmol, 0.070 g), H2L (0.2 mmol, 0.0397 g) and NaOH (0.1 mmol, 0.004 g) was dissolved in distilled water (10 mL).Then the mixture was transferred and sealed in a 25 mL Teflon-lined stainless steel container.The container was heated at 448 K for 4 days.After the mixture had been cooled to room temperature at a rate of 5 ℃·h-1, pale yellow crystals of 1 were obtained in 27% yield based on Zn(II).Anal.Calcd.for C27H21N5O9Zn (%): C, 51.90; H, 3.39; N, 11.21.Found (%): C, 51.38; H, 3.20; N, 11.02.IR (cm–1): 3444(m), 1645(s), 1563(w), 1526(w), 1407(m), 1361(w), 1136(s), 1311(w), 1080(w), 995(w), 951(w), 890(w), 863(w), 823(w), 772(w), 729(w), 618(m), 539(w), 519(w).

2.3 X-ray structure determination

A single crystal with dimensions of 0.19mm × 0.13mm × 0.10mm was chosen and mounted on a Rigaku RAXIS-RAPID diffractometer equipped with a graphite-monochromatized MoKα (λ = 0.71073 ?) radiation by using an w-f scan method at 293(2) K.Out of the 11996 total reflections collected in the 3.09≤θ≤27.48o range, 5499 were independent with Rint= 0.0468, of which 4658 were considered to be observed (I > 2σ(I)) and used in the succeeding refinement.The structure was solved by direct methods with SHELXS-97 program[12]and refined with SHELXL–97[13]by full-matrix least-squares techniques on F2.All H atoms were positioned geometrically (C–H = 0.93 ?) and refined as riding, with Uiso(H) = 1.2Ueq(carrier).The water hydrogen atoms were located from difference Fourier maps.The final R = 0.0474 and wR = 0.1352+ (0.0873P)2+ 0.1442P], where P =.S = 1.097, (Δρ)max= 0.930, (Δρ)min=–0.417 e/?3and (Δ/σ)max= 0.001.

3 RESULTS AND DISCUSSION

3.1 Description of the crystal structure

Selected bond lengths and bond angles for the title compound are given in Table 1.The asymmetric unit of 1 consists of one Zn(II) atom, one L2-anion, one IPP ligand, one coordination water molecule, and two free water molecules.As illustrated in Fig.1, each Zn(II) cation is five-coordinated by three oxygen atoms from one carboxylate, one phenolic hydroxyl and one water molecule (Zn(1)–O(1) = 1.9378(19), Zn(1)–O(2) = 1.913(2) and Zn(1)–O(1W) = 2.210(2) ?), and two nitrogen atoms (Zn(1)–N(1) = 2.009(2) and Zn(1)–N(2) = 2.027(2) ?) from one IPP ligand in a square pyramidal geometry.The N(1), N(2), O(1) and O(2) atoms constitute the equatorial plane, while the O(1)W is located on the vertex of the square pyramid.It is noteworthy that the phenolic hydroxyl and one carboxylate of the L2-anion coordinate to the Zn(II) atom, whereas the remaining carboxylate is free (Fig.1).The IPP ligand chelates the Zn(II) atom, adopting a bis-chelating coordination mode.Owing to the presence of aromatic IPP ligands, adjacent [Zn(L)(IPP)(H2O)]·2H2O molecules are linked into a supramolecular chain through π-π stackings between the two phenanthroline rings of the IPP ligands with the centroid-to-centroid distance of 3.58 ? and face-to-face distance of 3.47 ? (the two phenanthroline rings are composed of C(1)–C(1 2)/N(1)/N(2) a n d C(1)#1–C(12)#1/N(1)#1/N(2)#1, respectively; symmetry code:#12–x, –y, 1–z).As shown in Fig.2, N–H··O (N(4)–H(4) = 0.86, H(4)··O(4)#1= 1.98, N(4)··O(4)#1= 2.820(3) ?, DN(4)–H(4)··O(4)#1= 164.0o) and O–H··N hydrogen bonds (O(1W)–HW(12) = 0.833(10), HW(12)···N(3)#3= 1.999(11), O(1W)···N(3)#3= 2.822(3) ?, DO(1W)–H(W12)··N(3)#3= 169(3)o) (symmetric codes:#1–x+2, –y, –z+1;#3–x+1, –y, –z+1) further stabilize the supramolecular chain of 1 (Table 2).In the N(4)–H(4)…O(4)#1hydrogen bond, the imidazole N(4) atom acts as the H donor, and the carboxylate oxygen O(4)#1atom functions as the H acceptor.Nevertheless, in the O(1W)–HW(12)··N(3)#3hydrogen bond, the imidazole N(3)#3atom plays a role of the H acceptor, and the O(1W) acts as the H donor.In addition, the lattice O(3W) as the H donor interacts with the lattice O(2W) through the O(3W)–HW(31)··O(2W) hydrogen bond to form a (H2O)2dimer.The lattice O(2W) and O(3W) are further stabilized by carboxylate oxygen atoms through the O(2W)–HW(21)··O(4), O(2W)–HW(22)··O(4)#4and O(3W)–HW(32)··O(5)#5hydrogen bonds.

Fig.1.View of the dimeric structure of the title complex

Fig.2.View of the supramolecular chain of the title complex constructed by π-π and hydrogen-bonding interactions

Table 1.Selected Bond Lengths (?) and Bond Angles (°)

Table 2.Hydrogen Bond Lengths (?) and Bond Angles (°)

3.2 Luminescent properties

Coordination complexes with Zn(II) metal centers have potential applications in electroluminescent display, photochemistry and chemical sensors[14].In this work, solid state luminescent studies were conducted for H2L, IPP and 1.As shown in Fig.3, the main emission peaks of H2L and IPP are at 388 nm (λex= 325 nm) and 510 nm (λex= 325 nm), respectively.The emission bands of these free ligands are probably caused by π*-n or π*-π transitions[14].The emission peak of Zn(II)-containing compound 1 was observed at 552 nm (λex= 325 nm) that is red-shifted by 42 nm with respect to the band shown by L2-ligand because the coordination of L to Zn(II) decreases the π*-n or π*-π energy gap of the carboxylate ligand[14].

Fig.3.Emission spectra of H2L, IPP and compound 1 in the solid state at room temperature

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10.14102/j.cnki.0254-5861.2011-0682

11 February 2015; accepted 23 April 2015 (CCDC 1048425)

① Supported by the Institute Foundation of Siping City (No.2013036)

② Corresponding author.Majoring in coordination chemistry.E-mail: wangxiuyan2004@sohu.com